Event-by-Event Study of Prompt Neutrons from ²³⁹Pu

Conference · Mon Oct 26 04:00:00 EDT 2009

OSTI ID:972127

Vogt, R. ^[1]; Randrup, J. ^[2]; Pruet, J. ^[1]; Younes, W. ^[1]

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1. Lawrence Livermore National Laboratory (LLNL), Livermore, CA
2. Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

Employing a recently developed Monte Carlo model, we study the fission of ²⁴⁰Pu induced by neutrons with energies from thermal to just below the threshold for second chance fission. Current measurements of the mean number of prompt neutrons emitted in fission, together with less accurate measurements of the neutron energy spectra, place remarkably fine constraints on predictions of microscopic calculations. In particular, the total excitation energy of the nascent fragments must be specified to within 1 MeV to avoid disagreement with measurements of the mean neutron multiplicity. The combination of the Monte Carlo fission model with a statistical likelihood analysis also presents a powerful tool for the evaluation of fission neutron data. Of particular importance is the fission spectrum, which plays a key role in determining reactor criticality. We show that our approach can be used to develop an estimate of the fission spectrum with uncertainties several times smaller than current experimental uncertainties for outgoing neutron energies of less than 2 MeV.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA; Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP); National Science Foundation (NSF)
• DOE Contract Number: AC52-07NA27344; AC02-05CH11231
• OSTI ID: 972127
• Report Number(s): LLNL--CONF-423083
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
97 MATHEMATICS AND COMPUTING
CRITICALITY
ENERGY SPECTRA
EVALUATION
EXCITATION
FISSION
FISSION NEUTRONS
MULTIPLICITY
NEUTRONS
Nuclear Criticality Safety Program (NCSP)
PROMPT NEUTRONS